About October's Birthstone: Greeks believed Opals to give the bearer foresight and prophecy. A gift of Opals symbolizes hope, fidelity and assurance. Opals Bad Luck ? I think not, in 1890 it is noted that sour diamond merchants started the rumors of opals being bad luck since they were gaining in popularity and hurting the diamond trade. Opals are the suggested gift for the 14th and 34th wedding anniversary.